1. Field of the Invention
This invention relates to instrumentation for aligning a surgical tool, and primarily, although not exclusively relates to instrumentation for use in resecting the distal end of a humerus.
2. Discussion of the Related Art
When implanting a total joint prosthesis, it is necessary to resect the ends of the bones which meet at the joint. In the past, resecting has been carried out by eye and relied almost exclusively on the skill of the surgeon. More recently, instrumentation has been produced for resecting the femur or tibia for installation of a total knee prosthesis. Such instrumentation comprises a jig to which is fitted a rod. The rod is inserted into a bore drilled into the intramedullary canal and provides alignment of the jig with the longitudinal axis of the bone. One or more openings are provided in the jig for insertion of a drill bit or saw blade.
Although this conventional instrumentation provides reasonable alignment with the longitudinal axis of the bone, it does not provide rotational alignment of the jig about the longitudinal axis of the bone, so that the surgeon must have considerable skill and experience before he can carry out an accurate bone resection.
The problems of using the conventional instrumentation are accentuated if the distal end of the humerus is damaged by injury or disease, as it is not possible to use the distal end surface as an accurate reference to locate the normal axis of joint movement. The present invention seeks to address these problems.